Excavators and backhoes of conventional construction, e.g. as described in Horton U.S. Pat. No. 7,322,133, the complete disclosure of which is incorporated herein by reference, are known in the prior art. By way of example, and with reference to FIGS. 12A and 12B of the present application, a hydraulic excavator 100 has a chassis 114 with a cab 118 for the operator. Extending from the chassis 114 is a boom 122 pivotally attached to the chassis, and a dipper stick 124 pivotally attached at the outboard end of the boom 122. The dipper stick 124 connected to the boom arm 122 is moved in and out by means of a hydraulic boom cylinder 126. An excavator attachment, e.g., a multi-shank ripper excavator attachment or tool 112, as taught in the Horton '133 patent mentioned above, is removably connected to the dipper stick 124 at a stick pivot or pin 132 and to a 4-bar linkage 142 (connected to a hydraulic bucket cylinder 130) at a link pivot or pin 134.
As described above, and referring also to FIG. 4, excavator and backhoe attachments, such as buckets of different widths and types, e.g. ripper bucket 50 (FIG. 6), ripper 52 (FIGS. 8) and 112 (FIGS. 12A and 12B), and other tools, are typically connected to the machine stick 124 and to the link 142 by horizontal pins, i.e., stick or hinge pin 132 and link pin 134. The stick pin 132 is held in place by engagement of a cross bolt 150 in aligned cross drilled hole 154 through the stick pin 132 and an associated stick pin locking collar 156, and the link pin 134 is similarly held in place by engagement of a cross bolt 150 in aligned cross drilled hole 158 through the link pin 134 and an associated link pin locking collar 160. The stick pin locking collar 156 and the link pin locking collar 160 are welded to the mounting plate (or “ear”) surface 166 of the excavator attachment. In turn, the cross bolts are secured in place by cooperating threaded nuts 152 at the opposite side of the collar 156, thereby to resist rotation and movement of the pins 132, 134 relative to the excavator attachment (only one cross bolt 150 and threaded nut 152 are shown, by way of example). This arrangement is described and discussed below in more detail, e.g., with reference to FIG. 4).
In other implementations, e.g., referring to FIG. 12B, a quick change coupler 164 may be used in place of the excavator attachment 128, with the coupler 164 connected to the stick pivot pin 132 and link pin 134 by a set of two pins and an arrangement of hooks and locks that grab a second set of two pins mounted on the attachment.
In still another implementation, mechanical and hydraulic “pin-grabber” couplers can also simplify the action of connecting the excavator attachment 112 to the stick 124 and link 142.
Changing excavator attachments 112 on an excavator or backhoe 100 without use of a quick change coupler 164 is recognized as being very difficult. For example, the operator must use a punch pin and a hammer to pound the linkage attachment pins 132, 134 into place and out of place. When pounding the pins into place for a new connection, it is very difficult to align each pin so that the retention cross bolt holes 154, 158 through the pins 132, 134 and their respective locking collars 156, 160 are aligned, in order to receive the cross bolts 150. This method is known to be difficult, dangerous, messy, and to require two operators to accomplish it efficiently. Initially, to begin the process, the operator may gently rest the excavator attachment 112 on the ground; however, after a few short minutes, hydraulic valve spool leakage allows the combined weight of the stick 124 and boom 122 to cause the boom and stick to sag due to the hydraulic leakage drift. As a result, the entire weight of the stick and boom ends up resting on the linkage and attachment pins. During the changing operation, the operator tries to pound the pins 132, 134 out of place, but when one pin finally pops out, e.g. the stick pin 132, the stick 124 drops, and the punch pin (not shown) becomes trapped in the bucket bore, pinched by the stick. The operator must then get back into the machine cab and lift the 124 stick with the hydraulic power, thereby seeking to free the punch. The operator then has to pound the link pin 134 out of place in a similar fashion. After the first excavator attachment (e.g. tool 112) has been disconnected, the operator must swing the linkage over while attempting to align the stick bosses 170 (FIG. 4, where only one is seen) with the attachment bosses 172 (again, only one is seen). Most of the time, the second attachment is not sitting on a flat portion of the ground and it is not fully square to the machine, so aligning the stick 124 to the attachment bosses 172 is very difficult.
Once the stick and the replacement excavator attachment are aligned, the operator begins to pound the stick 132 into place from one side of the replacement attachment 112′, and then into the stick boss bore 170, to complete the pivot. Again, because the stick 124 and boom 122 begin to slowly drift and sag lower due to hydraulic valve spool leakage, aligning the attachment pin bore 172 to the link bore 170 is very difficult. After the stick pin 132 is finally engaged into one side of the stick bore 170, the pin must be pounded fully into place with a hammer until the end of the pin is visible on the opposite side of the attachment 112′. A cross bolt 150 is inserted to secure the pin 132 to the bucket 112′; however, it is very difficult to align the segments of locking bolt cross hole 158 (through the stick pin and through both sides of the stick pin locking collar 156) due to the weight of the stick 124 and boom 122 on the pin 132, so the weight must again be lifted off the stick 124, and the pin 132 rotated into alignment of the pin bolt hole segments so that the bolt 150 can be inserted. When the boom 122 and arm 120 are lifted, the weight of the attachment 112 again makes it difficult to rotate the pin 132, thus requiring more pounding and difficulty. After assembly of the stick pivot pin 132 is complete, the link pin 134 can be pounded into place, typically with a little less difficulty, but the task is still considered to be difficult and dangerous.
In fact, many equipment operators have suffered pinched, or even severed, fingers performing this operation. The task can also be very messy due to the grease covering the components. For these reasons, quick couplers 164 are recognized as a huge benefit to the industry. Additionally, use of quick couplers may allow some operators to change tools many times per day, so not having to pound pins into position is a huge benefit. The easier it is to change attachments, the more likely it is that an operator will change attachments frequently in order to employ the attachment best suited for the job being performed. In contrast, prior to use of quick change couplers, an operator often felt forced to continue to use a tool ill-suited for a segment of job, thereby to avoid the difficulty and downtime of making a change. As a result, having the ability to change attachments easily not only makes the job safer and faster for the operator, but it also makes the job more efficient and effective due to the increased frequency of use of the correct excavator attachment.
There are, however, situations in which the use of a quick change coupler 164 is not advantageous. For example, in digging and ripping applications, where the shortest tip radius is often desirous, using a quick change coupler may not be the best alternative because the coupler increases the tip radius, thus reducing the overall breakout force of the machine, e.g., use of a quick connect coupler can reduce breakout force by between 10% and 15%. Similarly, in other dig-and-load and lifting situations, a quick connect coupler 164 adds significant weight at the end of the stick 124, which decreases the payload that could otherwise be lifted safely. In addition, repeated lifting and lowering of a quick connect coupler increases fuel consumption and slows the cycle time of the digging operation, e.g. due to the extra weight. For example, a typical quick change coupler sized for use with 80 mm attachment pins weighs almost 1,000 pounds.
Hydraulic versions of pin-grabber couplers, e.g. as compared to mechanical versions, allow attachment changes to be made by an operator while remaining in the cab. However, the additional hydraulic valve and hydraulic plumbing of these couplers increases their complexity. These couplers and their plumbing components are also expensive, and introduce another possible source for contaminants in the hydraulic system. By way of example only, a typical hydraulic coupler for an excavator with 80 mm attachment pins may cost may cost as much as $8,000, not including the hydraulic kit, which can add another $4,000. The cost of a typical mechanical version of a pin-grabber coupler is, e.g., approximately $6,000.